var ary = [[1,2,3,4,5,6,7],[8,9,10],[11,12]]; var ary2 = Array.prototype.concat.apply([],ary); /* ary2 == [1,2,3,4,5,6,7,8,9,10,11,12]; */ Register as a new user and use Qiita more conveniently You get articles that match your needsYou can efficiently read back useful informationYou can use dark themeWhat you can do with signing up